Political spending set new records in 2012, which saw the first presidential election since the Supreme Courtís landmark Citizens United v. Federal Election Commission ruling.

Unrestricted super PACs and politically active advocacy groups spent more than $1 billion on campaign activities, and many found creative ways to avoid disclosing their funders. Some funneled campaign money through shell corporations, others took advantage of tax laws that allow 501(c)(4) social welfare groups and other nonprofits to keep their donors anonymous.

The year was marked by legal and regulatory battles over the campaign finance rules and numerous complaints from watchdogs to the IRS, the FEC and the Justice Department. Republicans went to court to roll back campaign finance limits further; Democrats sued to force the FEC to write stricter disclosure regulations. Lower court rulings sided first with one side, then with the other, creating confusion for political players. Proposed rules changes also fueled legislative battles on Capitol Hill, which are certain to continue in 2013.

Here are just a few of the political money turning points from 2012:

January

Jan. 11: Taking direct aim at a centerpiece of the campaign finance rules, the Republican National Committee argues in federal court that the ban on corporate contributions to candidates and parties is unconstitutional. The RNC files its brief before the Fourth Circuit Court of Appeals in a case known as U.S. v. Danielczyk.

February

Feb. 7: Having assailed unrestricted spending during the 2010 campaign, President Barack Obama signals he will now embrace Democrat-friendly super PACs.

Feb. 21: Billionaire casino mogul Sheldon Adelson announces he might spend $100 million to support former Speaker Newt Gingrich of Georgia in his presidential bid or another Republican. Adelson and his wife, Miriam, go on to give $91.8 million to super PACs in the 2012 cycle, making him the biggest individual campaign donor in U.S. history. By some estimates, Adelson also gives another $50 million to $65 million to non-disclosing tax-exempt groups by the campaignís end.

March 21: Senate Democrats introduce a stripped-down version of the DISCLOSE Act, which would require politically active outside organizations to more fully disclose their funding sources.

March 30: A federal judge agrees with Rep. Chris Van Hollen, D-Md., that FEC disclosure requirements for outside groups running issue ads are too lax. The judge orders the FEC to rewrite the rules and puts politically active nonprofits on notice that some of their ads will be subject to disclosure.